package bigdata.mapreduce;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Partitioner;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;

public class MergeSort {
	public MergeSort() {}
	
	public static class Map extends Mapper<Object,Text,IntWritable,NullWritable>{
		private static IntWritable data=new IntWritable();
		 @Override
		 public void map(Object key,Text value,Context context) 
				 throws IOException, InterruptedException {
			 String text=value.toString();
			 data.set(Integer.parseInt(text));
			 context.write(data, NullWritable.get());
		 }
	}
	
	public static class Partition extends Partitioner<IntWritable,NullWritable>{
		@Override
		public int getPartition(IntWritable key,NullWritable value,int num_Partition) {
			int Maxnumber =65535;
			int bound=Maxnumber/num_Partition+1;
			int keynumber=key.get();
			for(int i=0;i<num_Partition;i++) {
				if(keynumber<bound*(i+1) && keynumber>=bound*i) {
					return i;
				}
			}
			return -1;
		}
	}
	
	public static class Reduce extends Reducer<IntWritable,NullWritable,IntWritable,IntWritable>{
		private static IntWritable line_num=new IntWritable(1);
		@Override
		public void reduce(IntWritable key,Iterable<NullWritable> values,Context context) 
				throws IOException, InterruptedException {
			for(@SuppressWarnings("unused") NullWritable val:values) {
				context.write(line_num, key);
				line_num=new IntWritable(line_num.get()+1);
			}
		}
	}

	public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
		// TODO Auto-generated method stub
		Configuration conf=new Configuration();
		conf.set("fs.defaultFS", "hdfs://localhost:9000");
		String[] otherArgs=(new GenericOptionsParser(conf,args)).getRemainingArgs();
		if(otherArgs.length<2) {
			System.err.println("Usage:MergeSort<in>[<in>...] <out>");
			System.exit(2);
		}
//		else {
//			for(int i=0;i<otherArgs.length;i++) {
//				System.out.println(otherArgs[i].toString());			
//			}
//			System.out.println(WordCount.class.toString());
//			System.exit(0);
//		}	
		
		Job job=Job.getInstance(conf,"Merge Sort");
		job.setJarByClass(MergeSort.class);
		
		job.setMapperClass(MergeSort.Map.class);
		job.setReducerClass(MergeSort.Reduce.class);
		job.setPartitionerClass(MergeSort.Partition.class);
		
		job.setMapOutputKeyClass(IntWritable.class);
		job.setMapOutputValueClass(NullWritable.class);
		
		job.setOutputKeyClass(IntWritable.class);
		job.setOutputValueClass(IntWritable.class);
		
		for(int i=0;i<otherArgs.length-1;i++) {
			FileInputFormat.addInputPath(job, new Path(otherArgs[i]));			
		}
		
		FileOutputFormat.setOutputPath(job, new Path(otherArgs[otherArgs.length-1]));
		
		System.exit(job.waitForCompletion(true)?0:1);	
	}

}
